July 27, 20205 yr Having successfully installed my new controller and KT-LCD5 display, I'm exploring the 'Light Output' connection on the controller. It's a 2-pin red Julet connector and when the 'lights on' function is activated from the LCD5 display, the 2 pins have the main battery voltage present. Now, what exactly can you do with this output? The physical pin size is very small so one can't imagine much current can be passed (so what are the current limitations of the connector and indeed the controller?), and what lighting systems use such a (relatively) high voltage? Do you use the output to switch something else via a relay or other circuit? So I'd be very interested to know what others might use this particular output for? Many thanks in anticipation, cheers, B4t
July 27, 20205 yr Having successfully installed my new controller and KT-LCD5 display, I'm exploring the 'Light Output' connection on the controller. It's a 2-pin red Julet connector and when the 'lights on' function is activated from the LCD5 display, the 2 pins have the main battery voltage present. Now, what exactly can you do with this output? The physical pin size is very small so one can't imagine much current can be passed (so what are the current limitations of the connector and indeed the controller?), and what lighting systems use such a (relatively) high voltage? Do you use the output to switch something else via a relay or other circuit? So I'd be very interested to know what others might use this particular output for? Many thanks in anticipation, cheers, B4t [ATTACH type=full" alt="37266]37266[/ATTACH] The e-bike lighting that I have looked at, has a dropping resistor and a LED light. For example, my lights accept the 36 volts of my battery. Guessing a bit, I would expect that to be pretty normal. If I misunderstood your question, my apologies. regards Andy
July 28, 20205 yr Author Thanks [mention=20993]Andy-Mat[/mention] - a dropping resistor arrangement is simple I guess but very inefficient. However, given the power consumption of the lighting system vs that of the motor, a dropping resistor is a cheap and effective solution.
July 28, 20205 yr Thanks [mention=20993]Andy-Mat[/mention] - a dropping resistor arrangement is simple I guess but very inefficient. However, given the power consumption of the lighting system vs that of the motor, a dropping resistor is a cheap and effective solution. You got it immediately! My compliments! Many don't, but any extra power usage is hardly noticeable in comparison to the motor. Though I have not done any measurements, as it would just be a waste of my time. Plus, if a proper voltage dropper was installed, and it went wrong, finding something small and effective might prove difficult as there is not much room in some lights! I do not see the resistor as a problem myself, just like you! Andy
July 28, 20205 yr A resistor is completely the wrong way to go, not only will you waste 2 timess or 4 times as much power as the lights are using depebding on whether you use 12v or 6v lights, but your lithium battery voltage changes from full to empty, so your 12v lights will only get 8v when your battery is low. You can buy bicycle lights from Ebay, Aliexpress, Banggood and places like that that have an integral buck converter that can run on any DC voltage from 12v to 60v.
July 28, 20205 yr Is it possible to spur a fused feed off the battery if no light feed exists already. Are there any issues to consider?
July 28, 20205 yr Buy any light with a regulator in side and these lights cope well with a range of voltages from 6v to 60v. My current front and rear one on the bike simply wires in to my controller lights wiring and are STVZO rated. The front gives a superb lighting for night town riding and is very good for dull daylight riding, the rear a fixed light and very bright for dull/night riding. Cost about £12 each on AliExpress.
July 28, 20205 yr Is it possible to spur a fused feed off the battery if no light feed exists already. Are there any issues to consider? Yes, take a spur off the controller/battery feed and add a fuse in line after the controller on the voltage line between it and the light switch. Only my town/commute bike and my Swizzbee's have permanent lighting run off the battery, my other ebikes I use USB or 18650 lighting.
July 28, 20205 yr Fuse? are the spade type in rubber holder ok? what rating? Yes, that is the type I used with a small 3 - 5a rating as the silicone awg I use was only about 22/24awg.
July 28, 20205 yr A resistor is completely the wrong way to go, not only will you waste 2 timess or 4 times as much power as the lights are using depebding on whether you use 12v or 6v lights, but your lithium battery voltage changes from full to empty, so your 12v lights will only get 8v when your battery is low. You can buy bicycle lights from Ebay, Aliexpress, Banggood and places like that that have an integral buck converter that can run on any DC voltage from 12v to 60v. Till someone takes the time to measure and compare the losses between the two styles, with an identical LED, there is really no comparison, you are being over awed by the thought, not by actual values!! Furthermore, many lights are quoted in LUX only, which makes such calculations more difficult, unless the ACTUAL EXACT efficiency is also quoted, which it is on none that I have looked at! I know of no one that has done any comparison between a DC to DC converter and a resistor. Just to start you off:- Assuming a modern 1 Watt High Brightness LED is fitted, which requires around 140 ma, to have the best brightness and the best life. (My bike lights are actually some years old and are therefore probably less than 1 Watt, but still good..) More current than that will seriously reduce an average 1 Watt LED lifespan. Using a 36 volt battery as a power source, a dropping resistor needs to drop 32 volts on average. Power = Volts x amps = 32 x 0.140 = 4.48 Watts wasted in the resistor. A 230 Ohm resistor would be a good choice, rated at 5 watts or better. Comparing that to say a 250 Watt Bike motor, that is only around 1.78% of what the motor takes! In the big scheme of things, what physics professor will notice the difference for his battery's range in miles with light on and light off? None of them! I actually also have rechargeable extra lights on my bike, front and back, in case I ride too far and the main battery is empty....for any reason. Someone who gets on average say 50 miles per charge, and who rides with that light on all the time (some do!), and the motor always on, will lose LESS THAN A MILE OF RANGE!!! About 0.9 of a mile, 1,584 Yards. For anyone interested, here are the (simple) calculations for LEDs and various voltages:- https://dmohankumar.wordpress.com/2018/06/20/how-to-select-resistor-for-1-watt-led/ QED. Its simply not worth worrying about, as possibly just freewheeling down just one hill, will save enough power for the light for several miles! Also, the simple resistor will simply "shrug off" a possible drop or two of water, but an electronics circuit might simply short out and drain the battery, at the same time burning up the wiring! And I have never seen a fuse fitted in any bike lighting! Regards to all here Andy PS. do not forget that most bike lights around, are less than one watt, so in reality, the actual loses would be even less than I have calculated for an average 1 watt LED!
July 28, 20205 yr Till someone takes the time to measure and compare the losses between the two styles, with an identical LED, there is really no comparison, you are being over awed by the thought, not by actual values!! Furthermore, many lights are quoted in LUX only, which makes such calculations more difficult, unless the ACTUAL EXACT efficiency is also quoted, which it is on none that I have looked at! I know of no one that has done any comparison between a DC to DC converter and a resistor. Just to start you off:- Assuming a modern 1 Watt High Brightness LED is fitted, which requires around 140 ma, to have the best brightness and the best life. (My bike lights are actually some years old and are therefore probably less than 1 Watt, but still good..) More current than that will seriously reduce an average 1 Watt LED lifespan. Using a 36 volt battery as a power source, a dropping resistor needs to drop 32 volts on average. Power = Volts x amps = 32 x 0.140 = 4.48 Watts wasted in the resistor. A 230 Ohm resistor would be a good choice, rated at 5 watts or better. Comparing that to say a 250 Watt Bike motor, that is only around 1.78% of what the motor takes! In the big scheme of things, what physics professor will notice the difference for his battery's range in miles with light on and light off? None of them! I actually also have rechargeable extra lights on my bike, front and back, in case I ride too far and the main battery is empty....for any reason. Someone who gets on average say 50 miles per charge, and who rides with that light on all the time (some do!), and the motor always on, will lose LESS THAN A MILE OF RANGE!!! About 0.9 of a mile, 1,584 Yards. For anyone interested, here are the (simple) calculations for LEDs and various voltages:- https://dmohankumar.wordpress.com/2018/06/20/how-to-select-resistor-for-1-watt-led/ QED. Its simply not worth worrying about, as possibly just freewheeling down just one hill, will save enough power for the light for several miles! Also, the simple resistor will simply "shrug off" a possible drop or two of water, but an electronics circuit might simply short out and drain the battery, at the same time burning up the wiring! And I have never seen a fuse fitted in any bike lighting! Regards to all here Andy PS. do not forget that most bike lights around, are less than one watt, so in reality, the actual loses would be even less than I have calculated for an average 1 watt LED! It's a simple calculation. To drop from 36v to 6v is a factor of 6, so if you have a 5w bulb, the resistor needs to dissipate 30w. If you have a single 1w LED, which is a bit weak, the resisor needs to disipate 6w. I'm surprised that you couldn't work that out. Not only are your assumptions incorrect, but so is your calculation. How are you going to overcome the problem of reducing battery voltage.
July 28, 20205 yr In the big scheme of things, what physics professor will notice the difference for his battery's range in miles with light on and light off? None of them! Yes but, in this day and age with our increasingly environmental concerns we shouldn't be wasting any energy at all and this waste in total is a concern. Take the Netherlands where 70% of the population cycle daily, consider them riding home from work etc in winter, each with front AND rear lights (hopefully), and your calculations produce over 100 kW of energy wasted each evening. Add Germany and Denmark also with high cycling levels and very affected with dark evenings and the wastage grows considerably. On a related subject, the Japanese designers at Panasonic have an interesting way of wasting energy in voltage reduced bicycle lighting. Their 26 volt mid drive unit has a lighting takeoff fed by a high frequency voltage chopper to produce AC with a very uneven mark-space ratio to simulate a 6 volt supply over time from the 26 volt Li-ion. Useless for fast reacting LEDs of course, in bicycle designs it feeds tungsten filament 6 volt bulbs, their slow reaction time evening out the chopped current into a smooth flow by resistance wastage as heat. Clearly they weren't considering efficiency in combining the resistance method with electronic complexity! .
July 28, 20205 yr It's a simple calculation. To drop from 36v to 6v is a factor of 6, so if you have a 5w bulb, the resistor needs to dissipate 30w. If you have a single 1w LED, which is a bit weak, the resisor needs to disipate 6w. I'm surprised that you couldn't work that out. Not only are your assumptions incorrect, but so is your calculation. How are you going to overcome the problem of reducing battery voltage. You spell even worse that you calculate! In one short sentence, two spelling errors!!! (resisor needs to disipate) DUUUUHHHHH! Also, you apparently did not look at the web page I posted, as it states clearly that a 1 Watt LED needs only 3.6 volts! Industry standard. I used 4 volts to keep it simple for you! Obviously, not simple enough. Try a re-think and a re-calculation! If you need help, I can post the simple calculation for you, if you do not wish to look at the web page! Look at this web page:- https://www.pcboard.ca/led-dropping-resistor-calculator That makes it REALLY easy for you!
July 28, 20205 yr Yes but, in this day and age with our increasingly environmental concerns we shouldn't be wasting any energy at all and this waste in total is a concern. Take the Netherlands where 70% of the population cycle daily, consider them riding home from work etc in winter, each with front AND rear lights (hopefully), and your calculations produce over 100 kW of energy wasted each evening. Add Germany and Denmark also with high cycling levels and very affected with dark evenings and the wastage grows considerably. On a related subject, the Japanese designers at Panasonic have an interesting way of wasting energy in voltage reduced bicycle lighting. Their 26 volt mid drive unit has a lighting takeoff fed by a high frequency voltage chopper to produce AC with a very uneven mark-space ratio to simulate a 6 volt supply over time from the 26 volt Li-ion. Useless for fast reacting LEDs of course, in bicycle designs it feeds tungsten filament 6 volt bulbs, their slow reaction time evening out the chopped current into a smooth flow by resistance wastage as heat. Clearly they weren't considering efficiency in combining the resistance method with electronic complexity! . You have to find (easily) far more serious places to save power than that! The sheer number of TVs on standby, the SAT receivers on standby, all wasting in a day, far more power than any light on a bike for a few hours or riding when SOME times its switched on, are far more wasteful of power..... But please, if thats where and what you want to save, then please do... "Every little helps said the old lady, as she P*SSED in the sea!"
July 28, 20205 yr You have to find (easily) far more serious places to save power than that! The sheer number of TVs on standby, the SAT receivers on standby, all wasting in a day, far more power than any light on a bike for a few hours or riding when SOME times its switched on, are far more wasteful of power..... There's a difference, those so called wastes are often something being usefully done. Resistance waste in a bike lighting system isn't since it's unnecessary and has no gain. .
July 28, 20205 yr You spell even worse that you calculate! In one short sentence, two spelling errors!!! (resisor needs to disipate) DUUUUHHHHH! Also, you apparently did not look at the web page I posted, as it states clearly that a 1 Watt LED needs only 3.6 volts! Industry standard. I used 4 volts to keep it simple for you! Obviously, not simple enough. Try a re-think and a re-calculation! If you need help, I can post the simple calculation for you, if you do not wish to look at the web page! Look at this web page:- https://www.pcboard.ca/led-dropping-resistor-calculator That makes it REALLY easy for you! I don't need internet calculators, like you because I understand how it works, so I can do it in my head. They used to call it mental arithmetic. Of course you can only do that if you have the understanding and the mental capacity to multiply by 6. Also, the simple resistor will simply "shrug off" a possible drop or two of water, but an electronics circuit might simply short out and drain the battery, at the same time burning up the wiring! And I have never seen a fuse fitted in any bike lighting! That's right. the resistor will be fine when it dries out; however, your expensive light won't fare so well when it gets the entire battery voltage across it - should make a nice pop and maybe a bit of fizz too. BTW, you control LEDs by current, not by voltage. That's why you need driver circuits for them. Edited July 28, 20205 yr by vfr400
July 28, 20205 yr You spell even worse that you calculate! In one short sentence, two spelling errors!!! (resisor needs to disipate) DUUUUHHHHH! Also, you apparently did not look at the web page I posted, as it states clearly that a 1 Watt LED needs only 3.6 volts! Industry standard. I used 4 volts to keep it simple for you! Obviously, not simple enough. Try a re-think and a re-calculation! If you need help, I can post the simple calculation for you, if you do not wish to look at the web page! Look at this web page:- https://www.pcboard.ca/led-dropping-resistor-calculator That makes it REALLY easy for you! Many people, myself included, type quickly and mistakes do happen. With the amount of useful information that VFR pumps out to this forum I'm not surprised that there are sometimes spelling or grammatical errors. I think that bringing that into this thread is quite childish and unnecessary. Also, I don't know VFR at all, but what if he has dyslexia? Would be really big of you to insult him from behind your keyboard then wouldn't it? Edited July 28, 20205 yr by 01wellsd
July 28, 20205 yr Author '----------On a related subject, the Japanese designers at Panasonic have an interesting way of wasting energy in voltage reduced bicycle lighting. Their 26 volt mid drive unit has a lighting takeoff fed by a high frequency voltage chopper to produce AC with a very uneven mark-space ratio to simulate a 6 volt supply over time from the 26 volt Li-ion. Useless for fast reacting LEDs of course, in bicycle designs it feeds tungsten filament 6 volt bulbs, their slow reaction time evening out the chopped current into a smooth flow by resistance wastage as heat. Clearly they weren't considering efficiency in combining the resistance method with electronic complexity! . I'd be interested to read that article but from the way you describe the action of that device, it sounds like a switched mode power supply aka buck converter. These devices don't 'waste' voltage, they alter the voltage. The buck converter will in itself use some level of power - whether that is less or more than a simple dropping resistor requires some bench testing. And of course using a buck converter takes you into the realms of finding a location for it and any connectors, containers, waterproofing etc but does offer a more stable voltage for the lights as the bike battery discahrges say from 42v to 30v. As a very rough estimate, if the dropping resistor is sized to 'drop 5/6th of the battery terminal voltage, then the voltage available to the light will vary from 1/6th of 42v to 1/6th of 30v which is 7v and 5v respectively,which for LED lights may not even be noticeable. As a retired electronics person, I favour the more 'correct' buck converter approach, but the practical man in me is edging towards the dropping resistor(almost ) . I can fully understand why some folks just opt for clip-on lighting. More stealable but no additional cables and independant of the ebike battery (thinking flat battery scenario here). The little beastly below at around £4 uk pricing, could likely be found a home inside some light fittings.
July 28, 20205 yr Author Oh blimey - whilst I was typing the above, matters seem likely to be getting out of hand - thanks to all for your contributions and opinions though.
July 28, 20205 yr I'd be interested to read that article but from the way you describe the action of that device, it sounds like a switched mode power supply aka buck converter. These devices don't 'waste' voltage, they alter the voltage. The buck converter will in itself use some level of power - whether that is less or more than a simple dropping resistor requires some bench testing. And of course using a buck converter takes you into the realms of finding a location for it and any connectors, containers, waterproofing etc but does offer a more stable voltage for the lights as the bike battery discahrges say from 42v to 30v. As a very rough estimate, if the dropping resistor is sized to 'drop 5/6th of the battery terminal voltage, then the voltage available to the light will vary from 1/6th of 42v to 1/6th of 30v which is 7v and 5v respectively,which for LED lights may not even be noticeable. As a retired electronics person, I favour the more 'correct' buck converter approach, but the practical man in me is edging towards the dropping resistor(almost ) . I can fully understand why some folks just opt for clip-on lighting. More stealable but no additional cables and independant of the ebike battery (thinking flat battery scenario here). The little beastly below at around £4 uk pricing, could likely be found a home inside some light fittings. [ATTACH=full]37291[/ATTACH] The lights we mentioned earlier have built in buck converters specific to the lights as a ready-made solution. They're cheap, efficient and reliable - win win!
July 28, 20205 yr I'd be interested to read that article but from the way you describe the action of that device, it sounds like a switched mode power supply aka buck converter. These devices don't 'waste' voltage, they alter the voltage. There wasn't an article, Panasonic release no tech details on their pedelec designs, it comes from physical checking by a couple of us. It was quite a recent design and if they'd used a switched mode supply could have utilised LED lighting instead of wasting current in filament bulbs. However they didn't have to find space for a converter, the chopping was as I described and carried out in the all function circuit board with no voltage conversion. For lighting it was crude but it worked after a fashion, though nothing like as adequate as LED lighting. .
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